Introduction
RSS, or Really Simple Syndication, is a format designed to allow Web site content
to be easily syndicated. The syndicated content can be integrated into other Web sites, or can be
viewed by individuals via an assortment of desktop applications. For example, CNet's News.com
site can be syndicated, meaning you
can add the News.com's latest headlines to your Web site. A plethora of other Web sites, especially
blogs, provide this syndication feature. (For example, you can syndicate the content from the
myriad of Internet.com sites. Check out http://www.webreference.com/services/news/
for more information!)

In order to syndicate your Web site's content, all you need to do is create an RSS feed. An RSS feed
is a Web-accessible file those wishing to consume your content may access. The file must be an XML
file in the proper RSS standards format. Typically, an RSS feed is a static .xml that is
periodically updated by some background process, but you can use ASP or ASP.NET Web pages to
dynamically generate the RSS feed's content.

This article examines the RSS format and examines the RSS feed I created for ASPMessageboard.com.
This article also discusses how to consume RSS feeds using ASP, and mentions various programs you can
obtain to browse various RSS feeds from your desktop.

Creating an RSS Feed
The first step in syndicating your Web site's content is creating an RSS feed. Keep in mind that an
RSS feed is nothing more than an XML file that contains certain required tags.
An example RSS feed can be seen below:

Note that the RSS file has as its root the <rss> node. Following this there is
one <channel> node. Inside the channel node there must be the <title>,
<link>, and <description> nodes. The actual content that you want
to syndicate appears in <item> tags. Each <item> tag must
have at least an <title> or <description> tag.
(For a much more thorough discussion of the RSS spec, be sure to check out
http://backend.userland.com/rss.)

A site like CNN.com might have numerous RSS feeds: one for World news, one for US news, one for
Politics, one for Sports, and so on. Each RSS feed would then have, perhaps, 10 <item>
tags, one for each of the 10 latest stories. This RSS feed could be generated in one of two ways:

The feed could be generated as a static .xml file every half hour by some background process, or

The feed could be dynamically generated every time it is requested by having the RSS feed be an
ASP page that generates the needed XML

What option is the better one? Well, it depends on how often your content is updated. If you are only
adding new content once a day, or a couple times a day, then the static approach is likely to be ideal.
However, if the content you are adding changes frequently, a dynamic RSS feed might be the better
option.

Creating an RSS Feed for ASPMessageboard.com
I recently decided to add an XML feed to the ASPMessageboard.
Currently, the ASPMessageboard has a Recent
Questions page that lists the 25 most recently posted questions/answers on the messageboard. I thought
this would be a great item for syndication.

I started by creating a file named rss.asp, and then cut and pasted the code in from the
existing RecentQuestions.asp Web page. All I had to do was cut out the HTML and replace it
with the appropriate XML. The following code shows the germane parts of rss.asp:

One very important thing to realize is that XML files cannot contain <,
>, or & characters. Rather, they must be replaced by
&lt;, &gt;, and &amp;, respectively. (Technically,
XML files are also supposed to be free of apostrophes and double quotes, to be replaced with
&apos; and &quot, respectively. However, many XML parsers aren't
as strict about this condition.) Since these
forbidden characters may occur in the post's title, author, or body, before emitting any of these
values, they are passed through the ApplyXMLFormatting() function, which replaces any
occurrences of the offensive characters.

Also note that the <?xml version="1.0" encoding="ISO-8859-1"?> tag appears at
the top of the ASP page. This is because certain browsers, such as Mozilla, will complain if there
is any content before the <?xml ?> processing directive. Mozilla considers
even whitespace to be content that cannot appear before the directive. This is why
<?xml version="1.0" encoding="ISO-8859-1"?> goes at the very top.

Date Format for <lastBuildDate>

Alert 4Guys reader Kevin Latham notes that the date format is not correct for the
<lastBuildDate> date. Rather, the date format must appear in the following format:

DayAbbreviation, DayOfMonth MonthAbbreviation Year TimeInGMT

(This format can be seen in the RSS specs.)
I fixed this in the actual ASPMessageboard.com RSS feed by using a custom date formatting function
written by Ken Schaefer in the article A Customizable Date Formatting Routine.
(Note that I did not show this fix in the code example above because it would add much length to the code
example... just be sure you have your dates formatted properly.)

Consuming the Syndicated RSS Feed
Once you have syndicated your Web site's content using RSS you may wonder how others can consume the
syndicated material. Typically, RSS feeds are consumed by other Web sites. For example, using CNN's
RSS feed, one could add the latest headlines to their Web site. If you are interested in consuming
an RSS feed, check out the RSS Newsgrabber,
which is an ASP example authored by Eric Walters.
There's also examples in both ASP and ASP.NET by Stephen Travis at Gathering News Headline Feeds using ASP.

In addition to being able to consume RSS feeds via a Web interface, you can view RSS feeds via desktop
applications as well. For example, NewsGator, a commercial product,
provides RSS feed integration with Outlook. There are also free RSS feed readers, like
FreeReader.

Conclusion
In this article we examined how to syndicate Web site content using an RSS feed. Creating an RSS feed
for discretizable information is quite simple: all we need to do is place each unit of information
in an <item> tag. This is an especially easy task if your data is stored in a
database, as we saw by examining the RSS feed for ASPMessageboard.com.

Consuming an RSS Feed with ASP.NET

Consuming an RSS feed and displaying it in a DataGrid is insanely easy with ASP.NET! It's so
amazingly simple I decided to write an article about it:
Consuming an RSS Feed with ASP.NET.
Read on for more details!

When syndicating your site, if a user stumbles across the syndication feed through their web browser, they will see a jumble
of XML content. This can be confusing to novice computer users or those who are not familiar with syndication concepts.
You can alleviate this issue by using an XSL stylesheet to 'pretty up' your syndication feed's output when displayed through
a browser. Be sure to read Displaying Browser-Friendly RSS Feeds
for more information!